diff options
Diffstat (limited to 'vendor/golang.org/x/net/dns/dnsmessage/message.go')
| -rw-r--r-- | vendor/golang.org/x/net/dns/dnsmessage/message.go | 818 |
1 files changed, 709 insertions, 109 deletions
diff --git a/vendor/golang.org/x/net/dns/dnsmessage/message.go b/vendor/golang.org/x/net/dns/dnsmessage/message.go index c7244b7..dc5b143 100644 --- a/vendor/golang.org/x/net/dns/dnsmessage/message.go +++ b/vendor/golang.org/x/net/dns/dnsmessage/message.go @@ -5,6 +5,9 @@ // Package dnsmessage provides a mostly RFC 1035 compliant implementation of // DNS message packing and unpacking. // +// The package also supports messages with Extension Mechanisms for DNS +// (EDNS(0)) as defined in RFC 6891. +// // This implementation is designed to minimize heap allocations and avoid // unnecessary packing and unpacking as much as possible. package dnsmessage @@ -13,21 +16,11 @@ import ( "errors" ) -// Packet formats +// Message formats // A Type is a type of DNS request and response. type Type uint16 -// A Class is a type of network. -type Class uint16 - -// An OpCode is a DNS operation code. -type OpCode uint16 - -// An RCode is a DNS response status code. -type RCode uint16 - -// Wire constants. const ( // ResourceHeader.Type and Question.Type TypeA Type = 1 @@ -39,6 +32,7 @@ const ( TypeTXT Type = 16 TypeAAAA Type = 28 TypeSRV Type = 33 + TypeOPT Type = 41 // Question.Type TypeWKS Type = 11 @@ -46,7 +40,46 @@ const ( TypeMINFO Type = 14 TypeAXFR Type = 252 TypeALL Type = 255 +) +var typeNames = map[Type]string{ + TypeA: "TypeA", + TypeNS: "TypeNS", + TypeCNAME: "TypeCNAME", + TypeSOA: "TypeSOA", + TypePTR: "TypePTR", + TypeMX: "TypeMX", + TypeTXT: "TypeTXT", + TypeAAAA: "TypeAAAA", + TypeSRV: "TypeSRV", + TypeOPT: "TypeOPT", + TypeWKS: "TypeWKS", + TypeHINFO: "TypeHINFO", + TypeMINFO: "TypeMINFO", + TypeAXFR: "TypeAXFR", + TypeALL: "TypeALL", +} + +// String implements fmt.Stringer.String. +func (t Type) String() string { + if n, ok := typeNames[t]; ok { + return n + } + return printUint16(uint16(t)) +} + +// GoString implements fmt.GoStringer.GoString. +func (t Type) GoString() string { + if n, ok := typeNames[t]; ok { + return "dnsmessage." + n + } + return printUint16(uint16(t)) +} + +// A Class is a type of network. +type Class uint16 + +const ( // ResourceHeader.Class and Question.Class ClassINET Class = 1 ClassCSNET Class = 2 @@ -55,7 +88,44 @@ const ( // Question.Class ClassANY Class = 255 +) + +var classNames = map[Class]string{ + ClassINET: "ClassINET", + ClassCSNET: "ClassCSNET", + ClassCHAOS: "ClassCHAOS", + ClassHESIOD: "ClassHESIOD", + ClassANY: "ClassANY", +} + +// String implements fmt.Stringer.String. +func (c Class) String() string { + if n, ok := classNames[c]; ok { + return n + } + return printUint16(uint16(c)) +} +// GoString implements fmt.GoStringer.GoString. +func (c Class) GoString() string { + if n, ok := classNames[c]; ok { + return "dnsmessage." + n + } + return printUint16(uint16(c)) +} + +// An OpCode is a DNS operation code. +type OpCode uint16 + +// GoString implements fmt.GoStringer.GoString. +func (o OpCode) GoString() string { + return printUint16(uint16(o)) +} + +// An RCode is a DNS response status code. +type RCode uint16 + +const ( // Message.Rcode RCodeSuccess RCode = 0 RCodeFormatError RCode = 1 @@ -65,6 +135,116 @@ const ( RCodeRefused RCode = 5 ) +var rCodeNames = map[RCode]string{ + RCodeSuccess: "RCodeSuccess", + RCodeFormatError: "RCodeFormatError", + RCodeServerFailure: "RCodeServerFailure", + RCodeNameError: "RCodeNameError", + RCodeNotImplemented: "RCodeNotImplemented", + RCodeRefused: "RCodeRefused", +} + +// String implements fmt.Stringer.String. +func (r RCode) String() string { + if n, ok := rCodeNames[r]; ok { + return n + } + return printUint16(uint16(r)) +} + +// GoString implements fmt.GoStringer.GoString. +func (r RCode) GoString() string { + if n, ok := rCodeNames[r]; ok { + return "dnsmessage." + n + } + return printUint16(uint16(r)) +} + +func printPaddedUint8(i uint8) string { + b := byte(i) + return string([]byte{ + b/100 + '0', + b/10%10 + '0', + b%10 + '0', + }) +} + +func printUint8Bytes(buf []byte, i uint8) []byte { + b := byte(i) + if i >= 100 { + buf = append(buf, b/100+'0') + } + if i >= 10 { + buf = append(buf, b/10%10+'0') + } + return append(buf, b%10+'0') +} + +func printByteSlice(b []byte) string { + if len(b) == 0 { + return "" + } + buf := make([]byte, 0, 5*len(b)) + buf = printUint8Bytes(buf, uint8(b[0])) + for _, n := range b[1:] { + buf = append(buf, ',', ' ') + buf = printUint8Bytes(buf, uint8(n)) + } + return string(buf) +} + +const hexDigits = "0123456789abcdef" + +func printString(str []byte) string { + buf := make([]byte, 0, len(str)) + for i := 0; i < len(str); i++ { + c := str[i] + if c == '.' || c == '-' || c == ' ' || + 'A' <= c && c <= 'Z' || + 'a' <= c && c <= 'z' || + '0' <= c && c <= '9' { + buf = append(buf, c) + continue + } + + upper := c >> 4 + lower := (c << 4) >> 4 + buf = append( + buf, + '\\', + 'x', + hexDigits[upper], + hexDigits[lower], + ) + } + return string(buf) +} + +func printUint16(i uint16) string { + return printUint32(uint32(i)) +} + +func printUint32(i uint32) string { + // Max value is 4294967295. + buf := make([]byte, 10) + for b, d := buf, uint32(1000000000); d > 0; d /= 10 { + b[0] = byte(i/d%10 + '0') + if b[0] == '0' && len(b) == len(buf) && len(buf) > 1 { + buf = buf[1:] + } + b = b[1:] + i %= d + } + return string(buf) +} + +func printBool(b bool) string { + if b { + return "true" + } + return "false" +} + var ( // ErrNotStarted indicates that the prerequisite information isn't // available yet because the previous records haven't been appropriately @@ -90,6 +270,8 @@ var ( errTooManyAuthorities = errors.New("too many Authorities to pack (>65535)") errTooManyAdditionals = errors.New("too many Additionals to pack (>65535)") errNonCanonicalName = errors.New("name is not in canonical format (it must end with a .)") + errStringTooLong = errors.New("character string exceeds maximum length (255)") + errCompressedSRV = errors.New("compressed name in SRV resource data") ) // Internal constants. @@ -159,6 +341,19 @@ func (m *Header) pack() (id uint16, bits uint16) { return } +// GoString implements fmt.GoStringer.GoString. +func (m *Header) GoString() string { + return "dnsmessage.Header{" + + "ID: " + printUint16(m.ID) + ", " + + "Response: " + printBool(m.Response) + ", " + + "OpCode: " + m.OpCode.GoString() + ", " + + "Authoritative: " + printBool(m.Authoritative) + ", " + + "Truncated: " + printBool(m.Truncated) + ", " + + "RecursionDesired: " + printBool(m.RecursionDesired) + ", " + + "RecursionAvailable: " + printBool(m.RecursionAvailable) + ", " + + "RCode: " + m.RCode.GoString() + "}" +} + // Message is a representation of a DNS message. type Message struct { Header @@ -218,6 +413,7 @@ func (h *header) count(sec section) uint16 { return 0 } +// pack appends the wire format of the header to msg. func (h *header) pack(msg []byte) []byte { msg = packUint16(msg, h.id) msg = packUint16(msg, h.bits) @@ -270,28 +466,39 @@ type Resource struct { Body ResourceBody } +func (r *Resource) GoString() string { + return "dnsmessage.Resource{" + + "Header: " + r.Header.GoString() + + ", Body: &" + r.Body.GoString() + + "}" +} + // A ResourceBody is a DNS resource record minus the header. type ResourceBody interface { // pack packs a Resource except for its header. - pack(msg []byte, compression map[string]int) ([]byte, error) + pack(msg []byte, compression map[string]int, compressionOff int) ([]byte, error) // realType returns the actual type of the Resource. This is used to // fill in the header Type field. realType() Type + + // GoString implements fmt.GoStringer.GoString. + GoString() string } -func (r *Resource) pack(msg []byte, compression map[string]int) ([]byte, error) { +// pack appends the wire format of the Resource to msg. +func (r *Resource) pack(msg []byte, compression map[string]int, compressionOff int) ([]byte, error) { if r.Body == nil { return msg, errNilResouceBody } oldMsg := msg r.Header.Type = r.Body.realType() - msg, length, err := r.Header.pack(msg, compression) + msg, length, err := r.Header.pack(msg, compression, compressionOff) if err != nil { return msg, &nestedError{"ResourceHeader", err} } preLen := len(msg) - msg, err = r.Body.pack(msg, compression) + msg, err = r.Body.pack(msg, compression, compressionOff) if err != nil { return msg, &nestedError{"content", err} } @@ -436,7 +643,13 @@ func (p *Parser) Question() (Question, error) { // AllQuestions parses all Questions. func (p *Parser) AllQuestions() ([]Question, error) { - qs := make([]Question, 0, p.header.questions) + // Multiple questions are valid according to the spec, + // but servers don't actually support them. There will + // be at most one question here. + // + // Do not pre-allocate based on info in p.header, since + // the data is untrusted. + qs := []Question{} for { q, err := p.Question() if err == ErrSectionDone { @@ -492,7 +705,16 @@ func (p *Parser) Answer() (Resource, error) { // AllAnswers parses all Answer Resources. func (p *Parser) AllAnswers() ([]Resource, error) { - as := make([]Resource, 0, p.header.answers) + // The most common query is for A/AAAA, which usually returns + // a handful of IPs. + // + // Pre-allocate up to a certain limit, since p.header is + // untrusted data. + n := int(p.header.answers) + if n > 20 { + n = 20 + } + as := make([]Resource, 0, n) for { a, err := p.Answer() if err == ErrSectionDone { @@ -533,7 +755,16 @@ func (p *Parser) Authority() (Resource, error) { // AllAuthorities parses all Authority Resources. func (p *Parser) AllAuthorities() ([]Resource, error) { - as := make([]Resource, 0, p.header.authorities) + // Authorities contains SOA in case of NXDOMAIN and friends, + // otherwise it is empty. + // + // Pre-allocate up to a certain limit, since p.header is + // untrusted data. + n := int(p.header.authorities) + if n > 10 { + n = 10 + } + as := make([]Resource, 0, n) for { a, err := p.Authority() if err == ErrSectionDone { @@ -574,7 +805,16 @@ func (p *Parser) Additional() (Resource, error) { // AllAdditionals parses all Additional Resources. func (p *Parser) AllAdditionals() ([]Resource, error) { - as := make([]Resource, 0, p.header.additionals) + // Additionals usually contain OPT, and sometimes A/AAAA + // glue records. + // + // Pre-allocate up to a certain limit, since p.header is + // untrusted data. + n := int(p.header.additionals) + if n > 10 { + n = 10 + } + as := make([]Resource, 0, n) for { a, err := p.Additional() if err == ErrSectionDone { @@ -765,6 +1005,24 @@ func (p *Parser) AAAAResource() (AAAAResource, error) { return r, nil } +// OPTResource parses a single OPTResource. +// +// One of the XXXHeader methods must have been called before calling this +// method. +func (p *Parser) OPTResource() (OPTResource, error) { + if !p.resHeaderValid || p.resHeader.Type != TypeOPT { + return OPTResource{}, ErrNotStarted + } + r, err := unpackOPTResource(p.msg, p.off, p.resHeader.Length) + if err != nil { + return OPTResource{}, err + } + p.off += int(p.resHeader.Length) + p.resHeaderValid = false + p.index++ + return r, nil +} + // Unpack parses a full Message. func (m *Message) Unpack(msg []byte) error { var p Parser @@ -819,6 +1077,7 @@ func (m *Message) AppendPack(b []byte) ([]byte, error) { h.authorities = uint16(len(m.Authorities)) h.additionals = uint16(len(m.Additionals)) + compressionOff := len(b) msg := h.pack(b) // RFC 1035 allows (but does not require) compression for packing. RFC @@ -826,32 +1085,32 @@ func (m *Message) AppendPack(b []byte) ([]byte, error) { // unconditionally enabling it is fine. // // DNS lookups are typically done over UDP, and RFC 1035 states that UDP - // DNS packets can be a maximum of 512 bytes long. Without compression, - // many DNS response packets are over this limit, so enabling + // DNS messages can be a maximum of 512 bytes long. Without compression, + // many DNS response messages are over this limit, so enabling // compression will help ensure compliance. compression := map[string]int{} for i := range m.Questions { var err error - if msg, err = m.Questions[i].pack(msg, compression); err != nil { + if msg, err = m.Questions[i].pack(msg, compression, compressionOff); err != nil { return nil, &nestedError{"packing Question", err} } } for i := range m.Answers { var err error - if msg, err = m.Answers[i].pack(msg, compression); err != nil { + if msg, err = m.Answers[i].pack(msg, compression, compressionOff); err != nil { return nil, &nestedError{"packing Answer", err} } } for i := range m.Authorities { var err error - if msg, err = m.Authorities[i].pack(msg, compression); err != nil { + if msg, err = m.Authorities[i].pack(msg, compression, compressionOff); err != nil { return nil, &nestedError{"packing Authority", err} } } for i := range m.Additionals { var err error - if msg, err = m.Additionals[i].pack(msg, compression); err != nil { + if msg, err = m.Additionals[i].pack(msg, compression, compressionOff); err != nil { return nil, &nestedError{"packing Additional", err} } } @@ -859,37 +1118,104 @@ func (m *Message) AppendPack(b []byte) ([]byte, error) { return msg, nil } +// GoString implements fmt.GoStringer.GoString. +func (m *Message) GoString() string { + s := "dnsmessage.Message{Header: " + m.Header.GoString() + ", " + + "Questions: []dnsmessage.Question{" + if len(m.Questions) > 0 { + s += m.Questions[0].GoString() + for _, q := range m.Questions[1:] { + s += ", " + q.GoString() + } + } + s += "}, Answers: []dnsmessage.Resource{" + if len(m.Answers) > 0 { + s += m.Answers[0].GoString() + for _, a := range m.Answers[1:] { + s += ", " + a.GoString() + } + } + s += "}, Authorities: []dnsmessage.Resource{" + if len(m.Authorities) > 0 { + s += m.Authorities[0].GoString() + for _, a := range m.Authorities[1:] { + s += ", " + a.GoString() + } + } + s += "}, Additionals: []dnsmessage.Resource{" + if len(m.Additionals) > 0 { + s += m.Additionals[0].GoString() + for _, a := range m.Additionals[1:] { + s += ", " + a.GoString() + } + } + return s + "}}" +} + // A Builder allows incrementally packing a DNS message. +// +// Example usage: +// buf := make([]byte, 2, 514) +// b := NewBuilder(buf, Header{...}) +// b.EnableCompression() +// // Optionally start a section and add things to that section. +// // Repeat adding sections as necessary. +// buf, err := b.Finish() +// // If err is nil, buf[2:] will contain the built bytes. type Builder struct { - msg []byte - header header - section section + // msg is the storage for the message being built. + msg []byte + + // section keeps track of the current section being built. + section section + + // header keeps track of what should go in the header when Finish is + // called. + header header + + // start is the starting index of the bytes allocated in msg for header. + start int + + // compression is a mapping from name suffixes to their starting index + // in msg. compression map[string]int } -// Start initializes the builder. +// NewBuilder creates a new builder with compression disabled. // -// buf is optional (nil is fine), but if provided, Start takes ownership of buf. -func (b *Builder) Start(buf []byte, h Header) { - b.StartWithoutCompression(buf, h) - b.compression = map[string]int{} +// Note: Most users will want to immediately enable compression with the +// EnableCompression method. See that method's comment for why you may or may +// not want to enable compression. +// +// The DNS message is appended to the provided initial buffer buf (which may be +// nil) as it is built. The final message is returned by the (*Builder).Finish +// method, which may return the same underlying array if there was sufficient +// capacity in the slice. +func NewBuilder(buf []byte, h Header) Builder { + if buf == nil { + buf = make([]byte, 0, packStartingCap) + } + b := Builder{msg: buf, start: len(buf)} + b.header.id, b.header.bits = h.pack() + var hb [headerLen]byte + b.msg = append(b.msg, hb[:]...) + b.section = sectionHeader + return b } -// StartWithoutCompression initializes the builder with compression disabled. +// EnableCompression enables compression in the Builder. // -// This avoids compression related allocations, but can result in larger message -// sizes. Be careful with this mode as it can cause messages to exceed the UDP -// size limit. +// Leaving compression disabled avoids compression related allocations, but can +// result in larger message sizes. Be careful with this mode as it can cause +// messages to exceed the UDP size limit. // -// buf is optional (nil is fine), but if provided, Start takes ownership of buf. -func (b *Builder) StartWithoutCompression(buf []byte, h Header) { - *b = Builder{msg: buf} - b.header.id, b.header.bits = h.pack() - if cap(b.msg) < headerLen { - b.msg = make([]byte, 0, packStartingCap) - } - b.msg = b.msg[:headerLen] - b.section = sectionHeader +// According to RFC 1035, section 4.1.4, the use of compression is optional, but +// all implementations must accept both compressed and uncompressed DNS +// messages. +// +// Compression should be enabled before any sections are added for best results. +func (b *Builder) EnableCompression() { + b.compression = map[string]int{} } func (b *Builder) startCheck(s section) error { @@ -970,7 +1296,7 @@ func (b *Builder) Question(q Question) error { if b.section > sectionQuestions { return ErrSectionDone } - msg, err := q.pack(b.msg, b.compression) + msg, err := q.pack(b.msg, b.compression, b.start) if err != nil { return err } @@ -997,12 +1323,12 @@ func (b *Builder) CNAMEResource(h ResourceHeader, r CNAMEResource) error { return err } h.Type = r.realType() - msg, length, err := h.pack(b.msg, b.compression) + msg, length, err := h.pack(b.msg, b.compression, b.start) if err != nil { return &nestedError{"ResourceHeader", err} } preLen := len(msg) - if msg, err = r.pack(msg, b.compression); err != nil { + if msg, err = r.pack(msg, b.compression, b.start); err != nil { return &nestedError{"CNAMEResource body", err} } if err := h.fixLen(msg, length, preLen); err != nil { @@ -1021,12 +1347,12 @@ func (b *Builder) MXResource(h ResourceHeader, r MXResource) error { return err } h.Type = r.realType() - msg, length, err := h.pack(b.msg, b.compression) + msg, length, err := h.pack(b.msg, b.compression, b.start) if err != nil { return &nestedError{"ResourceHeader", err} } preLen := len(msg) - if msg, err = r.pack(msg, b.compression); err != nil { + if msg, err = r.pack(msg, b.compression, b.start); err != nil { return &nestedError{"MXResource body", err} } if err := h.fixLen(msg, length, preLen); err != nil { @@ -1045,12 +1371,12 @@ func (b *Builder) NSResource(h ResourceHeader, r NSResource) error { return err } h.Type = r.realType() - msg, length, err := h.pack(b.msg, b.compression) + msg, length, err := h.pack(b.msg, b.compression, b.start) if err != nil { return &nestedError{"ResourceHeader", err} } preLen := len(msg) - if msg, err = r.pack(msg, b.compression); err != nil { + if msg, err = r.pack(msg, b.compression, b.start); err != nil { return &nestedError{"NSResource body", err} } if err := h.fixLen(msg, length, preLen); err != nil { @@ -1069,12 +1395,12 @@ func (b *Builder) PTRResource(h ResourceHeader, r PTRResource) error { return err } h.Type = r.realType() - msg, length, err := h.pack(b.msg, b.compression) + msg, length, err := h.pack(b.msg, b.compression, b.start) if err != nil { return &nestedError{"ResourceHeader", err} } preLen := len(msg) - if msg, err = r.pack(msg, b.compression); err != nil { + if msg, err = r.pack(msg, b.compression, b.start); err != nil { return &nestedError{"PTRResource body", err} } if err := h.fixLen(msg, length, preLen); err != nil { @@ -1093,12 +1419,12 @@ func (b *Builder) SOAResource(h ResourceHeader, r SOAResource) error { return err } h.Type = r.realType() - msg, length, err := h.pack(b.msg, b.compression) + msg, length, err := h.pack(b.msg, b.compression, b.start) if err != nil { return &nestedError{"ResourceHeader", err} } preLen := len(msg) - if msg, err = r.pack(msg, b.compression); err != nil { + if msg, err = r.pack(msg, b.compression, b.start); err != nil { return &nestedError{"SOAResource body", err} } if err := h.fixLen(msg, length, preLen); err != nil { @@ -1117,12 +1443,12 @@ func (b *Builder) TXTResource(h ResourceHeader, r TXTResource) error { return err } h.Type = r.realType() - msg, length, err := h.pack(b.msg, b.compression) + msg, length, err := h.pack(b.msg, b.compression, b.start) if err != nil { return &nestedError{"ResourceHeader", err} } preLen := len(msg) - if msg, err = r.pack(msg, b.compression); err != nil { + if msg, err = r.pack(msg, b.compression, b.start); err != nil { return &nestedError{"TXTResource body", err} } if err := h.fixLen(msg, length, preLen); err != nil { @@ -1141,12 +1467,12 @@ func (b *Builder) SRVResource(h ResourceHeader, r SRVResource) error { return err } h.Type = r.realType() - msg, length, err := h.pack(b.msg, b.compression) + msg, length, err := h.pack(b.msg, b.compression, b.start) if err != nil { return &nestedError{"ResourceHeader", err} } preLen := len(msg) - if msg, err = r.pack(msg, b.compression); err != nil { + if msg, err = r.pack(msg, b.compression, b.start); err != nil { return &nestedError{"SRVResource body", err} } if err := h.fixLen(msg, length, preLen); err != nil { @@ -1165,12 +1491,12 @@ func (b *Builder) AResource(h ResourceHeader, r AResource) error { return err } h.Type = r.realType() - msg, length, err := h.pack(b.msg, b.compression) + msg, length, err := h.pack(b.msg, b.compression, b.start) if err != nil { return &nestedError{"ResourceHeader", err} } preLen := len(msg) - if msg, err = r.pack(msg, b.compression); err != nil { + if msg, err = r.pack(msg, b.compression, b.start); err != nil { return &nestedError{"AResource body", err} } if err := h.fixLen(msg, length, preLen); err != nil { @@ -1189,12 +1515,12 @@ func (b *Builder) AAAAResource(h ResourceHeader, r AAAAResource) error { return err } h.Type = r.realType() - msg, length, err := h.pack(b.msg, b.compression) + msg, length, err := h.pack(b.msg, b.compression, b.start) if err != nil { return &nestedError{"ResourceHeader", err} } preLen := len(msg) - if msg, err = r.pack(msg, b.compression); err != nil { + if msg, err = r.pack(msg, b.compression, b.start); err != nil { return &nestedError{"AAAAResource body", err} } if err := h.fixLen(msg, length, preLen); err != nil { @@ -1207,13 +1533,38 @@ func (b *Builder) AAAAResource(h ResourceHeader, r AAAAResource) error { return nil } -// Finish ends message building and generates a binary packet. +// OPTResource adds a single OPTResource. +func (b *Builder) OPTResource(h ResourceHeader, r OPTResource) error { + if err := b.checkResourceSection(); err != nil { + return err + } + h.Type = r.realType() + msg, length, err := h.pack(b.msg, b.compression, b.start) + if err != nil { + return &nestedError{"ResourceHeader", err} + } + preLen := len(msg) + if msg, err = r.pack(msg, b.compression, b.start); err != nil { + return &nestedError{"OPTResource body", err} + } + if err := h.fixLen(msg, length, preLen); err != nil { + return err + } + if err := b.incrementSectionCount(); err != nil { + return err + } + b.msg = msg + return nil +} + +// Finish ends message building and generates a binary message. func (b *Builder) Finish() ([]byte, error) { if b.section < sectionHeader { return nil, ErrNotStarted } b.section = sectionDone - b.header.pack(b.msg[:0]) + // Space for the header was allocated in NewBuilder. + b.header.pack(b.msg[b.start:b.start]) return b.msg, nil } @@ -1243,12 +1594,23 @@ type ResourceHeader struct { Length uint16 } -// pack packs all of the fields in a ResourceHeader except for the length. The -// length bytes are returned as a slice so they can be filled in after the rest -// of the Resource has been packed. -func (h *ResourceHeader) pack(oldMsg []byte, compression map[string]int) (msg []byte, length []byte, err error) { +// GoString implements fmt.GoStringer.GoString. +func (h *ResourceHeader) GoString() string { + return "dnsmessage.ResourceHeader{" + + "Name: " + h.Name.GoString() + ", " + + "Type: " + h.Type.GoString() + ", " + + "Class: " + h.Class.GoString() + ", " + + "TTL: " + printUint32(h.TTL) + ", " + + "Length: " + printUint16(h.Length) + "}" +} + +// pack appends the wire format of the ResourceHeader to oldMsg. +// +// The bytes where length was packed are returned as a slice so they can be +// updated after the rest of the Resource has been packed. +func (h *ResourceHeader) pack(oldMsg []byte, compression map[string]int, compressionOff int) (msg []byte, length []byte, err error) { msg = oldMsg - if msg, err = h.Name.pack(msg, compression); err != nil { + if msg, err = h.Name.pack(msg, compression, compressionOff); err != nil { return oldMsg, nil, &nestedError{"Name", err} } msg = packType(msg, h.Type) @@ -1293,6 +1655,44 @@ func (h *ResourceHeader) fixLen(msg []byte, length []byte, preLen int) error { return nil } +// EDNS(0) wire costants. +const ( + edns0Version = 0 + + edns0DNSSECOK = 0x00008000 + ednsVersionMask = 0x00ff0000 + edns0DNSSECOKMask = 0x00ff8000 +) + +// SetEDNS0 configures h for EDNS(0). +// +// The provided extRCode must be an extedned RCode. +func (h *ResourceHeader) SetEDNS0(udpPayloadLen int, extRCode RCode, dnssecOK bool) error { + h.Name = Name{Data: [nameLen]byte{'.'}, Length: 1} // RFC 6891 section 6.1.2 + h.Type = TypeOPT + h.Class = Class(udpPayloadLen) + h.TTL = uint32(extRCode) >> 4 << 24 + if dnssecOK { + h.TTL |= edns0DNSSECOK + } + return nil +} + +// DNSSECAllowed reports whether the DNSSEC OK bit is set. +func (h *ResourceHeader) DNSSECAllowed() bool { + return h.TTL&edns0DNSSECOKMask == edns0DNSSECOK // RFC 6891 section 6.1.3 +} + +// ExtendedRCode returns an extended RCode. +// +// The provided rcode must be the RCode in DNS message header. +func (h *ResourceHeader) ExtendedRCode(rcode RCode) RCode { + if h.TTL&ednsVersionMask == edns0Version { // RFC 6891 section 6.1.3 + return RCode(h.TTL>>24<<4) | rcode + } + return rcode +} + func skipResource(msg []byte, off int) (int, error) { newOff, err := skipName(msg, off) if err != nil { @@ -1317,6 +1717,7 @@ func skipResource(msg []byte, off int) (int, error) { return newOff, nil } +// packUint16 appends the wire format of field to msg. func packUint16(msg []byte, field uint16) []byte { return append(msg, byte(field>>8), byte(field)) } @@ -1335,6 +1736,7 @@ func skipUint16(msg []byte, off int) (int, error) { return off + uint16Len, nil } +// packType appends the wire format of field to msg. func packType(msg []byte, field Type) []byte { return packUint16(msg, uint16(field)) } @@ -1348,6 +1750,7 @@ func skipType(msg []byte, off int) (int, error) { return skipUint16(msg, off) } +// packClass appends the wire format of field to msg. func packClass(msg []byte, field Class) []byte { return packUint16(msg, uint16(field)) } @@ -1361,6 +1764,7 @@ func skipClass(msg []byte, off int) (int, error) { return skipUint16(msg, off) } +// packUint32 appends the wire format of field to msg. func packUint32(msg []byte, field uint32) []byte { return append( msg, @@ -1386,17 +1790,16 @@ func skipUint32(msg []byte, off int) (int, error) { return off + uint32Len, nil } -func packText(msg []byte, field string) []byte { - for len(field) > 0 { - l := len(field) - if l > 255 { - l = 255 - } - msg = append(msg, byte(l)) - msg = append(msg, field[:l]...) - field = field[l:] +// packText appends the wire format of field to msg. +func packText(msg []byte, field string) ([]byte, error) { + l := len(field) + if l > 255 { + return nil, errStringTooLong } - return msg + msg = append(msg, byte(l)) + msg = append(msg, field...) + + return msg, nil } func unpackText(msg []byte, off int) (string, int, error) { @@ -1422,6 +1825,7 @@ func skipText(msg []byte, off int) (int, error) { return endOff, nil } +// packBytes appends the wire format of field to msg. func packBytes(msg []byte, field []byte) []byte { return append(msg, field...) } @@ -1462,18 +1866,33 @@ func NewName(name string) (Name, error) { return n, nil } +// MustNewName creates a new Name from a string and panics on error. +func MustNewName(name string) Name { + n, err := NewName(name) + if err != nil { + panic("creating name: " + err.Error()) + } + return n +} + +// String implements fmt.Stringer.String. func (n Name) String() string { return string(n.Data[:n.Length]) } -// pack packs a domain name. +// GoString implements fmt.GoStringer.GoString. +func (n *Name) GoString() string { + return `dnsmessage.MustNewName("` + printString(n.Data[:n.Length]) + `")` +} + +// pack appends the wire format of the Name to msg. // // Domain names are a sequence of counted strings split at the dots. They end // with a zero-length string. Compression can be used to reuse domain suffixes. // // The compression map will be updated with new domain suffixes. If compression // is nil, compression will not be used. -func (n *Name) pack(msg []byte, compression map[string]int) ([]byte, error) { +func (n *Name) pack(msg []byte, compression map[string]int, compressionOff int) ([]byte, error) { oldMsg := msg // Add a trailing dot to canonicalize name. @@ -1525,7 +1944,7 @@ func (n *Name) pack(msg []byte, compression map[string]int) ([]byte, error) { // Miss. Add the suffix to the compression table if the // offset can be stored in the available 14 bytes. if len(msg) <= int(^uint16(0)>>2) { - compression[string(n.Data[i:])] = len(msg) + compression[string(n.Data[i:])] = len(msg) - compressionOff } } } @@ -1534,6 +1953,10 @@ func (n *Name) pack(msg []byte, compression map[string]int) ([]byte, error) { // unpack unpacks a domain name. func (n *Name) unpack(msg []byte, off int) (int, error) { + return n.unpackCompressed(msg, off, true /* allowCompression */) +} + +func (n *Name) unpackCompressed(msg []byte, off int, allowCompression bool) (int, error) { // currOff is the current working offset. currOff := off @@ -1569,6 +1992,9 @@ Loop: name = append(name, '.') currOff = endOff case 0xC0: // Pointer + if !allowCompression { + return off, errCompressedSRV + } if currOff >= len(msg) { return off, errInvalidPtr } @@ -1648,8 +2074,9 @@ type Question struct { Class Class } -func (q *Question) pack(msg []byte, compression map[string]int) ([]byte, error) { - msg, err := q.Name.pack(msg, compression) +// pack appends the wire format of the Question to msg. +func (q *Question) pack(msg []byte, compression map[string]int, compressionOff int) ([]byte, error) { + msg, err := q.Name.pack(msg, compression, compressionOff) if err != nil { return msg, &nestedError{"Name", err} } @@ -1657,6 +2084,14 @@ func (q *Question) pack(msg []byte, compression map[string]int) ([]byte, error) return packClass(msg, q.Class), nil } +// GoString implements fmt.GoStringer.GoString. +func (q *Question) GoString() string { + return "dnsmessage.Question{" + + "Name: " + q.Name.GoString() + ", " + + "Type: " + q.Type.GoString() + ", " + + "Class: " + q.Class.GoString() + "}" +} + func unpackResourceBody(msg []byte, off int, hdr ResourceHeader) (ResourceBody, int, error) { var ( r ResourceBody @@ -1709,6 +2144,11 @@ func unpackResourceBody(msg []byte, off int, hdr ResourceHeader) (ResourceBody, rb, err = unpackSRVResource(msg, off) r = &rb name = "SRV" + case TypeOPT: + var rb OPTResource + rb, err = unpackOPTResource(msg, off, hdr.Length) + r = &rb + name = "OPT" } if err != nil { return nil, off, &nestedError{name + " record", err} @@ -1728,8 +2168,14 @@ func (r *CNAMEResource) realType() Type { return TypeCNAME } -func (r *CNAMEResource) pack(msg []byte, compression map[string]int) ([]byte, error) { - return r.CNAME.pack(msg, compression) +// pack appends the wire format of the CNAMEResource to msg. +func (r *CNAMEResource) pack(msg []byte, compression map[string]int, compressionOff int) ([]byte, error) { + return r.CNAME.pack(msg, compression, compressionOff) +} + +// GoString implements fmt.GoStringer.GoString. +func (r *CNAMEResource) GoString() string { + return "dnsmessage.CNAMEResource{CNAME: " + r.CNAME.GoString() + "}" } func unpackCNAMEResource(msg []byte, off int) (CNAMEResource, error) { @@ -1750,16 +2196,24 @@ func (r *MXResource) realType() Type { return TypeMX } -func (r *MXResource) pack(msg []byte, compression map[string]int) ([]byte, error) { +// pack appends the wire format of the MXResource to msg. +func (r *MXResource) pack(msg []byte, compression map[string]int, compressionOff int) ([]byte, error) { oldMsg := msg msg = packUint16(msg, r.Pref) - msg, err := r.MX.pack(msg, compression) + msg, err := r.MX.pack(msg, compression, compressionOff) if err != nil { return oldMsg, &nestedError{"MXResource.MX", err} } return msg, nil } +// GoString implements fmt.GoStringer.GoString. +func (r *MXResource) GoString() string { + return "dnsmessage.MXResource{" + + "Pref: " + printUint16(r.Pref) + ", " + + "MX: " + r.MX.GoString() + "}" +} + func unpackMXResource(msg []byte, off int) (MXResource, error) { pref, off, err := unpackUint16(msg, off) if err != nil { @@ -1781,8 +2235,14 @@ func (r *NSResource) realType() Type { return TypeNS } -func (r *NSResource) pack(msg []byte, compression map[string]int) ([]byte, error) { - return r.NS.pack(msg, compression) +// pack appends the wire format of the NSResource to msg. +func (r *NSResource) pack(msg []byte, compression map[string]int, compressionOff int) ([]byte, error) { + return r.NS.pack(msg, compression, compressionOff) +} + +// GoString implements fmt.GoStringer.GoString. +func (r *NSResource) GoString() string { + return "dnsmessage.NSResource{NS: " + r.NS.GoString() + "}" } func unpackNSResource(msg []byte, off int) (NSResource, error) { @@ -1802,8 +2262,14 @@ func (r *PTRResource) realType() Type { return TypePTR } -func (r *PTRResource) pack(msg []byte, compression map[string]int) ([]byte, error) { - return r.PTR.pack(msg, compression) +// pack appends the wire format of the PTRResource to msg. +func (r *PTRResource) pack(msg []byte, compression map[string]int, compressionOff int) ([]byte, error) { + return r.PTR.pack(msg, compression, compressionOff) +} + +// GoString implements fmt.GoStringer.GoString. +func (r *PTRResource) GoString() string { + return "dnsmessage.PTRResource{PTR: " + r.PTR.GoString() + "}" } func unpackPTRResource(msg []byte, off int) (PTRResource, error) { @@ -1833,13 +2299,14 @@ func (r *SOAResource) realType() Type { return TypeSOA } -func (r *SOAResource) pack(msg []byte, compression map[string]int) ([]byte, error) { +// pack appends the wire format of the SOAResource to msg. +func (r *SOAResource) pack(msg []byte, compression map[string]int, compressionOff int) ([]byte, error) { oldMsg := msg - msg, err := r.NS.pack(msg, compression) + msg, err := r.NS.pack(msg, compression, compressionOff) if err != nil { return oldMsg, &nestedError{"SOAResource.NS", err} } - msg, err = r.MBox.pack(msg, compression) + msg, err = r.MBox.pack(msg, compression, compressionOff) if err != nil { return oldMsg, &nestedError{"SOAResource.MBox", err} } @@ -1850,6 +2317,18 @@ func (r *SOAResource) pack(msg []byte, compression map[string]int) ([]byte, erro return packUint32(msg, r.MinTTL), nil } +// GoString implements fmt.GoStringer.GoString. +func (r *SOAResource) GoString() string { + return "dnsmessage.SOAResource{" + + "NS: " + r.NS.GoString() + ", " + + "MBox: " + r.MBox.GoString() + ", " + + "Serial: " + printUint32(r.Serial) + ", " + + "Refresh: " + printUint32(r.Refresh) + ", " + + "Retry: " + printUint32(r.Retry) + ", " + + "Expire: " + printUint32(r.Expire) + ", " + + "MinTTL: " + printUint32(r.MinTTL) + "}" +} + func unpackSOAResource(msg []byte, off int) (SOAResource, error) { var ns Name off, err := ns.unpack(msg, off) @@ -1885,19 +2364,41 @@ func unpackSOAResource(msg []byte, off int) (SOAResource, error) { // A TXTResource is a TXT Resource record. type TXTResource struct { - Txt string // Not a domain name. + TXT []string } func (r *TXTResource) realType() Type { return TypeTXT } -func (r *TXTResource) pack(msg []byte, compression map[string]int) ([]byte, error) { - return packText(msg, r.Txt), nil +// pack appends the wire format of the TXTResource to msg. +func (r *TXTResource) pack(msg []byte, compression map[string]int, compressionOff int) ([]byte, error) { + oldMsg := msg + for _, s := range r.TXT { + var err error + msg, err = packText(msg, s) + if err != nil { + return oldMsg, err + } + } + return msg, nil +} + +// GoString implements fmt.GoStringer.GoString. +func (r *TXTResource) GoString() string { + s := "dnsmessage.TXTResource{TXT: []string{" + if len(r.TXT) == 0 { + return s + "}}" + } + s += `"` + printString([]byte(r.TXT[0])) + for _, t := range r.TXT[1:] { + s += `", "` + printString([]byte(t)) + } + return s + `"}}` } func unpackTXTResource(msg []byte, off int, length uint16) (TXTResource, error) { - var txt string + txts := make([]string, 0, 1) for n := uint16(0); n < length; { var t string var err error @@ -1909,9 +2410,9 @@ func unpackTXTResource(msg []byte, off int, length uint16) (TXTResource, error) return TXTResource{}, errCalcLen } n += uint16(len(t)) + 1 - txt += t + txts = append(txts, t) } - return TXTResource{txt}, nil + return TXTResource{txts}, nil } // An SRVResource is an SRV Resource record. @@ -1926,18 +2427,28 @@ func (r *SRVResource) realType() Type { return TypeSRV } -func (r *SRVResource) pack(msg []byte, compression map[string]int) ([]byte, error) { +// pack appends the wire format of the SRVResource to msg. +func (r *SRVResource) pack(msg []byte, compression map[string]int, compressionOff int) ([]byte, error) { oldMsg := msg msg = packUint16(msg, r.Priority) msg = packUint16(msg, r.Weight) msg = packUint16(msg, r.Port) - msg, err := r.Target.pack(msg, nil) + msg, err := r.Target.pack(msg, nil, compressionOff) if err != nil { return oldMsg, &nestedError{"SRVResource.Target", err} } return msg, nil } +// GoString implements fmt.GoStringer.GoString. +func (r *SRVResource) GoString() string { + return "dnsmessage.SRVResource{" + + "Priority: " + printUint16(r.Priority) + ", " + + "Weight: " + printUint16(r.Weight) + ", " + + "Port: " + printUint16(r.Port) + ", " + + "Target: " + r.Target.GoString() + "}" +} + func unpackSRVResource(msg []byte, off int) (SRVResource, error) { priority, off, err := unpackUint16(msg, off) if err != nil { @@ -1952,7 +2463,7 @@ func unpackSRVResource(msg []byte, off int) (SRVResource, error) { return SRVResource{}, &nestedError{"Port", err} } var target Name - if _, err := target.unpack(msg, off); err != nil { + if _, err := target.unpackCompressed(msg, off, false /* allowCompression */); err != nil { return SRVResource{}, &nestedError{"Target", err} } return SRVResource{priority, weight, port, target}, nil @@ -1967,10 +2478,17 @@ func (r *AResource) realType() Type { return TypeA } -func (r *AResource) pack(msg []byte, compression map[string]int) ([]byte, error) { +// pack appends the wire format of the AResource to msg. +func (r *AResource) pack(msg []byte, compression map[string]int, compressionOff int) ([]byte, error) { return packBytes(msg, r.A[:]), nil } +// GoString implements fmt.GoStringer.GoString. +func (r *AResource) GoString() string { + return "dnsmessage.AResource{" + + "A: [4]byte{" + printByteSlice(r.A[:]) + "}}" +} + func unpackAResource(msg []byte, off int) (AResource, error) { var a [4]byte if _, err := unpackBytes(msg, off, a[:]); err != nil { @@ -1988,7 +2506,14 @@ func (r *AAAAResource) realType() Type { return TypeAAAA } -func (r *AAAAResource) pack(msg []byte, compression map[string]int) ([]byte, error) { +// GoString implements fmt.GoStringer.GoString. +func (r *AAAAResource) GoString() string { + return "dnsmessage.AAAAResource{" + + "AAAA: [16]byte{" + printByteSlice(r.AAAA[:]) + "}}" +} + +// pack appends the wire format of the AAAAResource to msg. +func (r *AAAAResource) pack(msg []byte, compression map[string]int, compressionOff int) ([]byte, error) { return packBytes(msg, r.AAAA[:]), nil } @@ -1999,3 +2524,78 @@ func unpackAAAAResource(msg []byte, off int) (AAAAResource, error) { } return AAAAResource{aaaa}, nil } + +// An OPTResource is an OPT pseudo Resource record. +// +// The pseudo resource record is part of the extension mechanisms for DNS +// as defined in RFC 6891. +type OPTResource struct { + Options []Option +} + +// An Option represents a DNS message option within OPTResource. +// +// The message option is part of the extension mechanisms for DNS as +// defined in RFC 6891. +type Option struct { + Code uint16 // option code + Data []byte +} + +// GoString implements fmt.GoStringer.GoString. +func (o *Option) GoString() string { + return "dnsmessage.Option{" + + "Code: " + printUint16(o.Code) + ", " + + "Data: []byte{" + printByteSlice(o.Data) + "}}" +} + +func (r *OPTResource) realType() Type { + return TypeOPT +} + +func (r *OPTResource) pack(msg []byte, compression map[string]int, compressionOff int) ([]byte, error) { + for _, opt := range r.Options { + msg = packUint16(msg, opt.Code) + l := uint16(len(opt.Data)) + msg = packUint16(msg, l) + msg = packBytes(msg, opt.Data) + } + return msg, nil +} + +// GoString implements fmt.GoStringer.GoString. +func (r *OPTResource) GoString() string { + s := "dnsmessage.OPTResource{Options: []dnsmessage.Option{" + if len(r.Options) == 0 { + return s + "}}" + } + s += r.Options[0].GoString() + for _, o := range r.Options[1:] { + s += ", " + o.GoString() + } + return s + "}}" +} + +func unpackOPTResource(msg []byte, off int, length uint16) (OPTResource, error) { + var opts []Option + for oldOff := off; off < oldOff+int(length); { + var err error + var o Option + o.Code, off, err = unpackUint16(msg, off) + if err != nil { + return OPTResource{}, &nestedError{"Code", err} + } + var l uint16 + l, off, err = unpackUint16(msg, off) + if err != nil { + return OPTResource{}, &nestedError{"Data", err} + } + o.Data = make([]byte, l) + if copy(o.Data, msg[off:]) != int(l) { + return OPTResource{}, &nestedError{"Data", errCalcLen} + } + off += int(l) + opts = append(opts, o) + } + return OPTResource{opts}, nil +} |